Drain socket and drain socket-equipped toilet bowl

ABSTRACT

A drain socket includes a first connection part connected to a drain pipe of a toilet bowl; a second connection part connected to a drain piping in a floor or the like; and a drain channel body connecting the first connection part and the second connection part. The drain channel body includes an inclined part inclined to one side in the front-back direction toward a lower side. A restriction part is provided at an upstream end portion of the drain channel body. A surface of the restriction part located on the one side where the inclined part is inclined has a portion where a horizontal distance from a center C of the first connection part increases from the center of the surface in the left-right direction toward an end side of the surface in the left-right direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Japanese Application No. 2019-102195 filed May 31, 2019, the entire contents of which are incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to a drain socket and a drain socket-equipped toilet bowl.

BACKGROUND OF THE DISCLOSURE

Conventionally, a drain socket that connects a drain pipe part (drain pipe) of a toilet bowl and a drain piping provided in a floor or the like is known. The drain socket generally includes a first connection part connected to a drain pipe part of a toilet bowl, a second connection part connected to drain piping provided in a floor or the like, and a drain channel body part (drain channel body) connecting the first connection part and the second connection part. Some drain sockets have an inclined part inclined backward toward a downstream side. In a drain socket having such an inclined part, for example, JP 2008-184745 A describes a drain socket in which a restriction part is provided at an upstream end portion of a drain channel body part. In this drain socket, flush water from the drain pipe part of the toilet bowl is caused to collide with the restriction part to increase siphon force.

SUMMARY OF THE DISCLOSURE

In the above-described configuration, paper or the like flowing down together with the flush water easily gathers at a back portion of the restriction part. When paper or the like having gathered at the back portion of the restriction part is caught there, clogging may occur. Therefore, improvement has been desired.

The present disclosure has been completed based on the above-described circumstances, and an object thereof is to provide a drain socket in which paper or the like can be less likely to be caught at a restriction part.

A drain socket of the present disclosure includes: a first connection part connected to a drain pipe part of a toilet bowl; a second connection part connected to drain piping in a floor or the like; and a drain channel body part connecting the first connection part and the second connection part. The drain channel body part includes an inclined part inclined to one side in a front-back direction toward a lower side. A restriction part is provided at an upstream end portion of the drain channel body part. A surface of the restriction part located on the one side has a portion where a horizontal distance between a center of the first connection part and a side edge surface of the restriction part increases from a center of the surface in a left-right direction toward an end side of the surface in the left-right direction.

A drain socket-equipped toilet bowl according to the present disclosure includes a toilet bowl having a drain pipe part of the toilet bowl; and the above-described drain socket.

The one side in the front-back direction in the present disclosure is a direction on a horizontal plane when the inclination direction of the inclined part is projected on the horizontal plane. The left-right direction in the present disclosure is a direction crossing the front-back direction in the present disclosure. The up-down direction in the present disclosure is an up-down direction in a state in which the drain socket is installed (a state in which the second connection part is connected to the drain piping in a floor or the like).

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view showing a drain socket, in which the drain socket connects a drain pipe part of a toilet bowl and drain piping in a floor, according to some embodiments;

FIG. 2 is a sectional view showing the drain socket, according to some embodiments;

FIG. 3 is a plan view showing an upper member of a hanging pipe of the drain socket, according to some embodiments;

FIG. 4 is a diagram illustrating the flow of water in the drain socket, according to some embodiments;

FIG. 5 is a cross-sectional view showing a drain socket according to some embodiments; and

FIG. 6 is a partially enlarged plan view showing the drain socket, according to some embodiments.

DETAILED DESCRIPTION OF THE DISCLOSURE

In the drain socket of the present disclosure, a surface of the inclined part on a side opposite to the one side may have a gradient closer to vertical on the downstream side than on the upstream side. According to such a configuration, flush water that has collided with a portion of the restriction part located on the one side and rebounded on the surface of the inclined part on the side opposite to the one side is drained vigorously due to the gradient close to vertical of the downstream side of the surface on the side opposite to the one side of the inclined part. Therefore, paper or the like can be less likely to be caught at the drain channel body part.

In the drain socket of the present disclosure, an inclined surface may be provided on a downstream side of the surface of the restriction part on the one side, the inclined surface being inclined to the side opposite to the one side toward a lower side in a vertical direction. According to such a configuration, flush water that has collided with the portion of the restriction part located on the one side flows down along the inclined surface to the surface of the inclined part on the side opposite to the one side, and flows down vigorously along the surface of the inclined part on the side opposite to the one side. Thus, the siphon force can be increased.

In the drain socket of the present disclosure, the portion of the restriction part located on the one side may have a step surface extending in a direction crossing the vertical direction. According to such a configuration, a large amount of flush water can collide with the portion of the restriction part located on the one side so that water film can be reliably formed. Thus, a siphon can be reliably generated.

In the drain socket of the present disclosure, in a state in which the first connection part is connected to the drain pipe part of the toilet bowl, the portion of the restriction part located on the one side is located on the one side relative to a portion, located on the one side, of the drain pipe part of the toilet bowl. In other words, at the one side of the toilet bowel, an outer edge of the drain pipe is located inside an inner edge of the restriction portion with respect to a horizontal configuration of the drain pipe and the restriction portion. According to such a configuration, as compared with the case where the portion of the restriction part located on the one side is located on the side opposite to the one side relative to the portion, located on the one side, of the drain pipe part of the toilet bowl, the flush water that has collided with the portion of the restriction part located on the one side goes to a lower position of the surface of the inclined part on the side opposite to the one side. Accordingly, the flush water that has collided with the portion of the restriction part located on the one side and the flush water that flows down from the drain pipe part of the toilet bowl join together at the lower position of the inclined part. As a result, a water film formation position where siphon occurs is lowered, so that the siphon force can be increased.

Below, some embodiments are described with reference to FIGS. 1 to 4.

In some embodiments a shown for example in FIGS. 1-4, a drain socket 10 includes a first connection part 11 connected to a drain pipe part (referred to as a toilet bowl drain pipe part 40) of a toilet bowl 41, a second connection part 12 connected to drain piping 50 in a floor, and a drain channel body part (drain channel body) 13 connecting the first connection part 11 and the second connection part 12.

In the following description of each component, the left side in FIG. 1 (an inclination direction of an inclined part 14) is back, the right side in FIG. 1 is front, the upper side in FIG. 1 is upper, and the lower side in FIG. 1 is lower, based on the orientation of a person sitting on the toilet bowl 41 in a normal posture. Further, in a direction perpendicular to the paper surface in FIG. 1, the front side of the paper surface is right, and the back side of the paper surface is left.

The toilet bowl 41 has a bowl part 42 and a toilet bowl drain channel 43 extending from a bottom part of the bowl part 42 toward the back side of the toilet bowl 41. The toilet bowl drain channel 43 extends obliquely upward from the bottom part of the bowl part 42, then extends downward, and opens vertically downward at its downstream end. The downstream end of the toilet bowl drain channel 43 is formed in the toilet bowl drain pipe part 40. The toilet bowl drain pipe part 40 has a cylindrical shape, and protrudes vertically downward at a back end portion of the toilet bowl 41.

The drain socket 10 has a hanging pipe 15 having the first connection part 11, an adjuster pipe 16 extending substantially horizontally from a lower end portion of the hanging pipe 15, and a connecting pipe 17 connected to a distal end portion of the adjuster pipe 16. The connecting pipe 17 has the second connection part 12. In the drain socket 10, the horizontal distance between the first connection part 11 and the second connection part 12 can be changed by cutting the adjuster pipe 16 to a predetermined length.

A lower end portion of the hanging pipe 15 is provided with a bent part 18. The bent part 18 is bent in an arc shape. Water accumulates in the bent part 18 so that a siphon action occurs.

The hanging pipe 15 is divided into an upper member 15U and a lower member 15S. A lower end of the upper member 15U is inserted into an upper end of the lower member 15S and joined by an adhesive. The adjuster pipe 16 is formed integrally with the lower member 15S. The bent part 18 is formed in the lower member 15S.

The first connection part 11 has a cylindrical shape and is opened to both upper and lower sides. The toilet bowl drain pipe part 40 is inserted into the first connection part 11 from above. A packing 60 is mounted on an outer peripheral surface of the first connection part 11.

As shown in FIG. 2, the packing 60 has a packing body part 61 externally fitted to the first connection part 11, and a seal part 62 protruding inward from an upper end of the packing body part 61. The seal part 62 has an annular shape and is in close contact with the entire circumference of the toilet bowl drain pipe part 40 (see FIG. 1).

The second connection part 12 has a cylindrical shape and is opened in the vertical direction. The second connection part 12 is continuous with a downstream end of the drain channel body part 13. The second connection part 12 is inserted into the drain piping 50.

The drain channel body part 13 extends over the hanging pipe 15, the adjuster pipe 16, and the connecting pipe 17. The drain channel body part 13 includes the inclined part 14, the bent part 18 continuous with the downstream side of the inclined part 14, a horizontal part 19 continuous with the downstream side of the bent part 18, and a vertical part 21 continuous with the downstream side of the horizontal part 19. The flow channel area of the drain channel body part 13 is substantially constant over the inclined part 14, the bent part 18, the horizontal part 19, and the vertical part 21. That is, the inner diameter dimension is substantially constant over the inclined part 14 and bent part 18 of the hanging pipe 15, the adjuster pipe 16, and the connecting pipe 17.

The inclined part 14 is formed in the upper member 15U of the hanging pipe 15. The inclined part 14 is inclined with respect to the vertical direction. The inclined part 14 is inclined backward toward the downstream side, as shown in FIG. 2. The inclined part 14 is displaced backward little by little from the upper end toward the lower end.

As shown in FIG. 2, a front surface (a surface on the side opposite to the one side) 22 of the inclined part 14 is located on a side facing a restriction part back portion 31. The front surface 22 of the inclined part 14 has a gradient closer to vertical on the downstream side 22S than on the upstream side 22U. In other words, the front surface 22 is more inclined from the vertical direction on an upstream 22U side than on a downstream side 22S. As shown in FIG. 2, the cross-sectional shape of the front surface 22 of the inclined part 14 is curved in an arcuate shape bulging backward. When viewed from above in the vertical direction, a lower end of the downstream side 22S of the front surface 22 is linear in the left-right direction as shown in FIG. 3.

A restriction part 30 is provided at an upstream end portion of the drain channel body part 13. The restriction part 30 has first and second step surfaces 33 and 34 each of which extends in a direction crossing the vertical direction (substantially in a horizontal direction). The second step surface 34 is located on the downstream side of the first step surface 33. The width dimension (dimension in the inner-outer direction) of the second step surface 34 is smaller than that of the first step surface 33, as shown in FIG. 3.

As shown in FIG. 3, the first step surface 33 has an annular shape formed on the entire circumference of the restriction part 30. The first step surface 33 has first side step surfaces 33S located on both left and right sides of the restriction part 30, a first front step surface 33F located on the front side of the restriction part 30, and a first back step surface 33R located on the back side of the restriction part 30. The width dimension (dimension in the inner-outer direction) of the first back step surface 33R gradually decreases from the center of the first back step surface 33R in the left-right direction toward the end sides of the first back step surface 33R in the left-right direction.

As shown in FIG. 3, the second step surface 34 has second side step surfaces 34S located on both left and right sides of the restriction part 30, and a second back step surface 34R located on the back side of the restriction part 30. The second side step surfaces 34S and the second back step surface 34R have substantially the same width dimension (dimension in the inner-outer direction).

As shown in FIG. 3, a peripheral surface of the restriction part 30 has a pair of left and right side surfaces 35, a front surface (a front side edge surface) 36, and a back surface (a back side edge surface) 37. The front surface 36 connects the front end sides of the pair of left and right side surfaces 35. The back surface 37 connects the back end sides of the pair of left and right side surfaces 35. The back surface 37 of the restriction part 30 is a surface of the restriction part 30 located on the one side where the inclined part 14 is inclined.

The pair of side surfaces 35 hangs down substantially vertically from inner edges of the pair of first side step surfaces 33S. As shown in FIG. 3, the pair of side surfaces 35 are substantially parallel and extend linearly in the front-back direction, in plan view from above. The front surface 36 hangs down substantially vertically from an inner edge of the first front step surface 33F. The front surface 36 is curved in an arc shape centered on the center C of the first connection part 11 in plan view from above. The back surface 37 hangs down substantially vertically from an inner edge of the first back step surface 33R. The back surface 37 will be described later in detail.

As shown in FIG. 3, a portion of the restriction part 30 located on the one side (referred to as a restriction part back portion 31) has the first back step surface 33R, the second back step surface 34R, and the back surface 37. The back surface 37 forms a peripheral surface of the restriction part back portion 31. As shown in FIG. 3, the back surface 37 is curved in an arc shape having a radius larger than that of the front surface 36 in plan view from above. In the back surface 37, a horizontal distance B1 between left and right ends 37L and 37R and the center C of the first connection part 11 is larger than a distance B2 between the center of the back surface 37 in the left-right direction and the center C of the first connection part 11. A horizontal distance between the restriction part back portion 31 and the center C of the first connection part 11 gradually increases from the center of the restriction part back portion 31 in the left-right direction toward both ends 37R and 37L. The restriction part 30 is symmetric left and right with respect to the center C of the first connection part 11.

As shown in FIG. 2, an inclined surface 38 that is inclined frontward toward the lower side in the vertical direction is provided on the downstream side of the restriction part back portion 31. The inclined surface 38 hangs down from an inner edge of the second back step surface 34R (see FIG. 3). The inclined surface 38 extends from the inner edge of the second back step surface 34R to an upstream end of the inclined part 14 of the drain channel main body 13. The inclined surface 38 is inclined toward the downstream side 22S of the front surface 22 of the inclined part 14. In other words, as shown in FIG. 2, a virtual inclined surface 39 extending downward along the inclined surface 38 crosses the downstream side 22S of the front surface 22 of the inclined part 14. The inclined surface 38 is inclined more than the front surface 36 of the restriction part 30 which faces the inclined surface 38.

The inclined surface 38 is curved in an arc shape substantially parallel to the back surface 37, as shown in FIG. 3. That is, a horizontal distance between both ends of the inclined surface 38 in the left-right direction and the center C of the first connection part 11 is larger than that between the center of the inclined surface 38 in the left-right direction and the center C of the first connection part 11.

Below, some examples of use of the drain socket 10 according to some embodiments are described.

First, as shown in FIG. 1, the toilet bowl drain pipe part 40 and the drain piping 50 are connected using the drain socket 10. The second connection part 12 of the drain socket 10 is connected to the drain piping 50, and the toilet bowl drain pipe part 40 is inserted into the first connection part 11. A lower end of the toilet bowl drain pipe part 40 protrudes downward relative to the lower end of the seal part 62 of the packing 60.

In a state in which the first connection part 11 is connected to the toilet bowl drain pipe part 40, the restriction part back portion 31 is located behind a back portion (a portion located on the one side) 44 of the toilet bowl drain pipe part 40, as shown in FIG. 1. In other words, a horizontal distance between the restriction part back portion 31 and the front surface 22 of the inclined part 14 is larger than that between the back portion 44 of the toilet bowl drain pipe part 40 and the front surface 22 of the inclined part 14.

As shown in FIG. 4, the water discharged from the toilet bowl drain pipe part 40 collides with the restriction part back portion 31, and forms a water film W1 on the downstream side, so that a siphon occurs early. The water that has collided with the restriction part back portion 31 flows down by the inclined surface 38 to the downstream side 22S, as indicated by arrow X. The flush water that has flowed down from the restriction part back portion 31 joins the flush water that has flowed down from the toilet bowl drain pipe part 40 as shown by arrow Y in the downstream side 22S, so that a water film W2 is formed. Since the water film forming position is thus low, a strong siphon force is generated. The water that has flowed down to the downstream side 22S vigorously flows into the bent part 18 as indicated by arrow Z along a nearly vertical inclination of the downstream side 22S. Thus, the water is strongly pulled downward, so that the siphon force becomes stronger.

In addition, paper or the like flowing down with the water gathers at the restriction part back portion 31. Here, since the restriction part back portion 31 expands in the left-right direction more largely than in the case where the restriction part back portion 31 has an arcuate surface, paper or the like is less likely to concentrate at the center. Further, since the flow channel area in the restriction part 30 is larger than that in the case where the restriction part back portion 31 has an arcuate surface, paper or the like flows down without being caught. Paper or the like is drawn down vigorously with water by the strong siphon force, and discharged smoothly.

Next, the operation and effects of some embodiments configured as described above will be described.

The drain socket 10, in some embodiments, includes the first connection part 11 connected to the drain pipe part (drain pipe) of the toilet bowl 41, the second connection part 12 connected to the drain piping 50 in the floor, and the drain channel body part (drain channel body) 13 connecting the first connection part 11 and second connection part 12. The drain channel body part 13 includes the inclined part 14 inclined backward toward the downstream side. A restriction part 30 is provided at an upstream end portion of the drain channel body part 13. The back surface (back edge surface) 37 of the restriction part 30 has a shape such that the horizontal distance B1 between both ends 37L and 37R in the left-right direction and the center C of the first connection part 11 is larger than the horizontal distance B2 between the center of the back surface 37 in the left-right direction and the center C of the first connection part 11. According to this configuration, in the back surface 37 of the restriction part 30, both end portions thereof in the left-right direction are located on more outer sides as compared with the case where the back surface 37 has an arc shape having a constant horizontal distance from the center C of the first connection part 11. Therefore, paper or the like is less likely to concentrate at the center of the back surface 37 of the restriction part 30, and easily flows down since the flow channel area is large. Thus, the paper or the like can be less likely to be caught at the restriction part back portion 31.

The front surface 22 of the inclined part 14 has a gradient closer to vertical on the downstream side than on the upstream side. According to this configuration, the flush water that has flowed down from the restriction part back portion 31 to the front surface 22 of the inclined part 14 is drained vigorously due to the gradient close to vertical of the downstream side of the front surface 22. Therefore, paper or the like can be less likely to be caught at the drain channel body part 13.

The inclined surface 38 that is inclined frontward toward the lower side in the vertical direction is provided on the downstream side of the back surface 37 of the restriction part 30. According to this configuration, the flush water that has collided with the restriction part back portion 31 flows down along the inclined surface 38 to the front surface 22 of the inclined part 14, and flows down vigorously along the front surface 22. Thus, the siphon force can be increased.

The restriction part back portion 31 has the first and second step surfaces 33 and 34 each of which extends in a direction crossing the vertical direction. According to this configuration, a large amount of flush water collides with the restriction part back portion 31, and thus the siphon force can be increased.

In a state in which the first connection part 11 is connected to the toilet bowl drain pipe part 40, the restriction part back portion 31 is located behind the back portion 44 of the toilet bowl drain pipe part 40. According to this configuration, as compared with the case where the restriction part back portion 31 is located ahead of the back portion 44 of the toilet bowl drain pipe part 40, the flush water that has rebounded from the restriction part back portion 31 goes to a lower position of the inclined part 14. Accordingly, the flush water that has collided with and rebounded from the restriction part back portion 31 and the flush water that flows down from the toilet bowl drain pipe part 40 join together at the lower position of the inclined part 14. As a result, a water film formation position where siphon occurs is lowered, so that the siphon force can be increased.

Below, a drain socket 70 according to some embodiments is described with reference to FIGS. 5 and 6.

The drain socket 70 may be different from one or more other drain socket embodiments described herein in that drain socket 70 may, in some embodiments, not include an adjuster part. Same or similar components as those in drain socket 10 are denoted by the same reference numerals, and redundant descriptions thereof are omitted.

The drain socket 70 may include, in a same or similar manner as described above with respect to drain socket 10, the first connection part 11, the second connection part 12, and/or the drain channel body part 13. In a same or similar manner as described above with respect to drain socket 10, the drain channel body part 13 has the inclined part 14, and the restriction part 30 is provided at the upstream end portion of the drain channel body part 13. In the following description of each component, the direction in which the inclined part 14 is inclined toward the lower side (left side in FIG. 5) is back, the opposite direction (right side in FIG. 5) is front, the upper side in FIG. 5 is upper, and the lower side in FIG. 5 is lower. Further, in a direction perpendicular to the paper surface in FIG. 5, the front side of the paper surface is right, and the back side of the paper surface is left.

In the drain channel main body part 13, the vertical part 21 is continuous with the downstream side of the inclined part 14. In a same or similar manner as described above with respect to drain socket 10, the front surface 22 of the inclined part 14 has a gradient closer to vertical on the downstream side 22S than on the upstream side 22U.

In a same or similar manner as described above with respect to drain socket 10, the restriction part 30 has the first and second step surfaces 33 and 34 each of which extends in a direction crossing the vertical direction (substantially in a horizontal direction).

In a same or similar manner as described above with respect to drain socket 10, the first step surface 33 has an annular shape formed on the entire circumference of the restriction part 30, and has the first side step surfaces 33S, the first front step surface 33F, and the first back step surface 33R. The first front step surfaces 33F and the first back step surface 33R have substantially the same width dimension (dimension in the inner-outer direction).

The second step surface 34 has the second side step surfaces 34S located on both left and right sides of the restriction part 30, and the second front step surface 71 located on the front side of the restriction part 30. The second side step surfaces 34S and the second front step surface 71 have substantially the same width dimension (dimension in the inner-outer direction).

The peripheral surface of the restriction part 30 has the pair of left and right side surfaces 35, the front surface 36, and the back surface 37, in a same or similar manner as described above with respect to drain socket 10.

The restriction part back portion 31 has the first back step surface 33R and the back surface 37. In a same or similar manner as described above with respect to drain socket 10, the back surface 37 is in some embodiments curved in an arc shape having a radius larger than that of the front surface 36 in plan view from above.

In a same or similar manner as described above with respect to drain socket 10, the inclined surface 38 that is inclined frontward toward the lower side in the vertical direction is in some embodiments provided on the downstream side of the restriction part back portion 31. The inclined surface 38 hangs down from the lower end of the back surface 37. In a same or similar manner as described above with respect to drain socket 10, the inclined surface 38 is in some embodiments inclined toward the downstream side 22S of the front surface 22 of the inclined part 14.

In a same or similar manner as described above with respect to drain socket 10, the inclined surface 38 in some embodiments has a shape such that a horizontal distance between both ends of the inclined surface 38 in the left-right direction and the center C of the first connection part 11 is larger than that between the center of the inclined surface 38 in the left-right direction and the center C of the first connection part 11. The inclined surface 38 is curved in an arc shape that is gentler than that of the back surface 37 in plan view from above. That is, the inclined surface 38 has a radius larger than that of the back surface 37.

As described above, in some embodiments, both end portions of the restriction part back portion 31 in the left-right direction are located on more outer sides, so that paper or the like is less likely to concentrate at the center of the restriction part back portion 31, in a same of similar manner as described with reference to drain socket 10, and paper or the like easily flows down since the flow channel area is large. Thus, the paper or the like can be less likely to be caught at the back portion of the restriction part 30.

In a same or similar manner as described above with respect to drain socket 10, the inclined surface 38 that is inclined frontward toward the lower side in the vertical direction is in some embodiments provided on the downstream side of the restriction part back portion 31. According to this configuration, the flush water that has abutted against the restriction part back portion 31 flows down along the inclined surface 38 to the front surface 22 of the inclined part 14, and flows down vigorously along the front surface 22. Thus, the siphon force can be increased.

The restriction part back portion 31 has the first step surface 33 extending in a direction crossing the vertical direction. According to this configuration, a large amount of flush water collides with the restriction part back portion 31, and thus the siphon force can be increased.

The present disclosure is not limited to the embodiments described by the above description and drawings, and the following embodiments are also included in the technical scope of the present disclosure.

Some descriptions herein have described the cases where the present disclosure is applied to the drain sockets 10 and 70 each of which is connected to the drain piping 50 provided in the floor. However, the present disclosure can also be applied to a drain socket for wall drain, which is connected to drain piping provided in a wall standing substantially perpendicular to the floor.

In some embodiments, the restriction part 30 has the first and second step surfaces 33 and 34, but the present disclosure is not limited thereto. The restriction part may have a tapered surface, instead of the step surfaces, in which the flow channel area is reduced toward the downstream side. Further, the restriction part may have three or more step surfaces.

In some embodiments, the front surface 22 of the inclined part 14 has a gradient closer to vertical on the downstream side than on the upstream side. However, the gradient of the front surface of the inclined part does not necessarily have to be designed in this manner.

In some embodiments, the inclined surface 38 is provided on the downstream side of the restriction part back portion 31, but the inclined surface does not necessarily have to be provided.

In some embodiments, the pair of side surfaces 35 is substantially parallel, and extends linearly in the front-back direction, but the present disclosure is not limited thereto. The pair of side surfaces may be, for example, gently curved.

In some embodiments, the back surface 37 has an arc shape, but the present disclosure is not limited thereto. The back surface has only to have a portion where a horizontal distance from the center of the first connection part increases from the center of the back surface in the left-right direction toward the end sides of the back surface. That is, such a portion may be formed in at least a part of the back surface.

In some embodiments described herein, the inclined part 14 of the drain socket 10 (or 70) may be inclined backward of the toilet bowl 41 toward the lower side, but the present disclosure is not limited thereto. The inclined part of the drain socket may be inclined in any direction in the horizontal direction toward the lower side. For example, the inclined part of the drain socket may be inclined frontward, leftward or rightward of the toilet bowl toward the lower side.

In some embodiments, the inclined part 14 is inclined backward toward the downstream side, but, the present disclosure is not limited thereto. The inclined part 14 may be inclined frontward toward the downstream side. 

What is claimed is:
 1. A drain socket comprising: a first connection part connected to a drain pipe of a toilet bowl having a front side and a back side; a second connection part connected to a drain piping; a drain channel body connecting the first connection part and the second connection part, the drain channel body comprising an inclined part inclined to with respect a vertical direction, so that a lower end thereof is positioned more toward one of the front side or the back side of the toilet bowl than a upper end thereof; and a restriction part provided at an upstream end portion of the drain channel body, wherein the restriction part extends inwardly toward a center of the first connection part so as to have a side edge surface at the one, and in a plan view of the restriction part, the side edge surface is curved such that a distance between the center of the first connection part and the side edge surface increases from a middle of the side edge surface toward ends of the side edge surface in the plan view.
 2. The drain socket of claim 1, wherein a surface of the inclined part on a side opposite to the one is more inclined from the vertical direction on an upstream side than on a downstream side.
 3. The drain socket of claim 1, wherein an inclined surface is provided on a downstream side of the side edge surface of the restriction part, the inclined surface being inclined to a side opposite to the one toward a lower side in the vertical direction.
 4. The drain socket of claim 1, wherein a portion of the restriction part located on the one has a step surface extending in a direction crossing the vertical direction.
 5. The drain socket of claim 1, wherein at the one of the toilet bowl, an outer edge of the drain pipe is located inside an inner edge of the restriction portion with respect to a horizontal configuration of the drain pipe and the restriction portion.
 6. A drain socket-equipped toilet bowl, comprising: a toilet bowl having a drain pipe of the toilet bowl; and the drain socket of claim
 1. 7. A drain socket comprising: a first connection part connected to a drain pipe of a toilet bowl having a front side and a back side; a second connection part connected to a drain piping; a drain channel body connecting the first connection part and the second connection part, the drain channel body comprising an inclined part inclined to with respect a vertical direction, so that a lower end thereof is positioned more toward one of the front side or the back side of the toilet bowl than a upper end thereof; and a restriction part provided at an upstream end portion of the drain channel body, wherein a surface of the restriction part located on the one has a portion where a horizontal distance between a center of the first connection part and a side edge surface of the restriction part increases from a center of the surface in a left-right direction toward an end side of the surface in the left-right direction.
 8. The drain socket of claim 7, wherein a surface of the inclined part on a side opposite to the one has a gradient closer to vertical on a downstream side than on an upstream side.
 9. The drain socket of claim 7, wherein an inclined surface is provided on a downstream side of the side edge surface of the restriction part, the inclined surface being inclined to a side opposite to the one toward a lower side in the vertical direction.
 10. The drain socket of claim 7, wherein a portion of the restriction part located on the one has a step surface extending in a direction crossing the vertical direction.
 11. The drain socket of claim 7, wherein a portion of the restriction part located on the one is located on the one relative to a portion, located on the one, of the drain pipe part of the toilet bowl. 